Any activity that deprives the brain of oxygen has the potential to cause moderate to severe brain cell death leading to permanent loss of neurological function ranging from difficulty in concentration or loss of short term memory capacity through severe, lifelong mental disability to death.

California blackout: Bend over with hands on knees and take ten deep breaths. Stand up and hold your breath after the tenth breath and have someone place their palms on either side of your wind pipe pressing gently constricting the arteries to your brain causing one to passout.